Insulated inner container for a fire resistant file cabinet

ABSTRACT

An insulated inner container for a fire resistive filing cabinet useful for the protection of easily damageable materials, such as magnetic tapes and microfilms, against the damaging effects of heat and high humidity. The walls of this insulated inner container include a layer of a chemical which undergoes an endothermic reaction upon the application of heat thereto. Heat transfer from the outer metal layers to the inner metal layers of the inner container walls is reduced through the use of a thermal barrier of heat resistive material which fills a groove formed around the covered opening into the container.

United States Patent Anderson et al.

l l INSULATED INNER CONTAINER FOR A FIRE RESISTANT FILE CABINET [75] Inventors; Clarence A. F. Anderson, Fruitport; Robert A. Laird. Muskegnn. both of Mich.

I73] Assignec; Shaw-Walker Company, Muskegon,

Mich.

[221 Filed: Feb. 28, l974 [Zll Apple No.: 446,592

[52] US. Cl. 3l2/2l4; l09/80; 220/9 F [5 l] Int. Cl E04b 2/34; 865d 25/l8 [58] Field of Search 220/9 R, 9 F. l0; 109/80, [09/81 84; 3l2/2l4 [56] References Cited UNITED STATES PATENTS 3,272,580 9/1966 Dean et al 3l2/2l4 3.408.966 ll/l968 Gartncr l09/80 3,709,169 l/l973 Gaugcr ct al. 109/80 June 10, 1975 3.761787 Ill/I973 Gruhh .l 3l2/2l4 Primary E.taminerWi|liam I. Price Assistant ExuminerBruce H. Bernstein Almrney. Agent or I-irm-Kinzer, Plyer. Dorn &

McEachran [5 7] ABSTRACT An insulated inner container for a fire resistive filing cabinet useful for the protection of easily damageable materials, such as magnetic tapes and microfilms. against the damaging effects of heat and high humidity. The walls of this insulated inner container include a layer of a chemical which undergoes an endothermic reaction upon the application of heat thereto. Heat transfer from the outer metal layers to the inner metal layers of the inner container walls is reduced through the use of a thermal barrier of heat resistive material which fills a groove formed around the covered opening into the container PATENTEDJUH 1 0 ms 1 I i l l l t L 'l M M ifrurli M ii. I m\ 7/////////////////// M INSULATED INNER CONTAINER FOR A FIRE RESISTANT FILE CABINET SUMMARY OF THE INVENTION This invention is directed to an inner insulated container for use with a tire resisthe filing cabinet to protect data storage materials such as microfilm and magnetic tape from the deleterious effects of heat and humidity which may build-up inside a fire resistive filing cabinet when it is subjected to fire.

An object of this invention is a lightweight insulated inner container for a fire resistive filing cabinet which protects easily damageable contents against the deleterious effects of heat and humidity.

Another object is an insulated inner container for a fire resistive filing cabinet which container is formed with hollow metal walls filled with an insulating material and a chemical which undergoes an endothermic reaction upon the application of heat thereto.

Another object is an inner insulated container having hollow metal walls constructed so that the heat does not readily flow from the outer surfaces to the inner surfaces of the walls over the open top of the container.

Other objects may be found in the following specification. claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a partial, cross-sectional view of an insulated inner container for a fire resistive filing cabinet emboding the no el features of this invention; and

FIG. 2 is a partial top plan view of the inner insulated container with its cover removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT The insulated inner container 11 of this invention may be designed for use with either a conventional insulated fire resistive filing cabinet 13 or an insulated fire resistive filing cabinet of the lateral type. An insulated fire resistive filing cabinet includes an insulated casing or housing 15 which may have two or more separate compartments 17 formed therein. While a filing cabinet seldom has less than two compartments, it should be understood that this invention may also be used with an insulated fire resistive storage unit having only a single compartment.

An opening 19 formed in the side of the casing 15 opens into each compartment 17. A drawer 21 is movable in and out of a compartment 17 on rollers and tracks which may be of conventional construction and, for clarity of illustration. are not shown in these drawings. The opening I9 into the compartment is closed by a drawer head 23 which may also be of conventional construction.

The insulated inner container II is mounted on a drawer 21 and moves with the drawer in and out of a compartment I7. The container 11 includes a lower portion 27 having an open top which is enclosed by a removable cover 29 which is also insulated. The lower portion of the container is constructed with hollow bottom. side and end walls. The hollow walls are formed of inner panels 31 and outer panels 33, both of which may be made of sheet metal. The outer panel 33 is made in sections with a bottom sheet 35 riveted to side and end sheets 37.

The void space between the inner and outer panels of the walls is filled with an insulating material 41 and a chemical 43 which undergoes an endothermic reaction upon the application of heat thereto. In this cmbodimcnt of the invention. the insulating material 4] is a rigid foamed plastic. preferably foamed polyurethane of two pound density formed in layers of one-half inch thickness. The insulating material is installed between the inner and outer panels in two layers abutting the outer panels 33 of the walls. The chemical which undergoes an endothermic reaction is crystalline sodium thiosulfate and it is positioned in a layer which is in contact with the inner panels 31 of the walls. The insulating material and the sodium thiosulfate are separated by aluminum foil 45.

A groove 49 is formed in the insulation 41 around the top of the lower portion 27 of the insulated inner container II. The edge portions 51 and 53 of the inner and outer panels 31 and 33 are bent over the top of the insulation and turned down into the groove 49. The groove is filled to the top level of the insulation with a sealant 55 which functions as a thermal barrier. In this embodiment of the invention. the thermal barrier is an adhesive sealant sold by the Dow Corning Corporation of Midland, Michigan. under the name SILASTIC 732 RTV."

The insulated removable cover 29 is also hollow, being constructed with an inner panel 61 and an outer panel 63. The ends of the outer panel 63 are turned in to form the sides and end walls of the cover and these ends extend behind the inner panel 61. A layer of polyurethane tape 65 is positioned against the under surfaces of the turned in edges of the outer panel 63. A gasket 69 made of silicone rubber is positioned against the layer of polyurethane tape and is held in position by threaded fasteners (not shown). The inner panel 61 fits in a pocket in this gasket and is also held by the threaded fasteners. The one-half inch layers of insulating material which in this embodiment also is foamed polyurethane of two pound density is located in the cover abutting the outer panel 63. A layer of crystalline sodium thiosulfate is positioned against the inner panel 61. The insulating materials and the sodium thiosulfate are separated by a layer of aluminum foil.

A metal skirt 77 hands downwardly from the rear wall fo the cover 29 to overhang the top of the lower portion 27 of the inner container when the cover is in its closed position. Panels 79 attached to the cover 29 extend downwardly on opposite sides thereof to also overhang the top of the lower portion 27 of the inner container.

The Use. Operation and Function of this Invention are as follows:

Although a properly designed and constructed insulated fire resistive filing cabinet satisfactorily protects papers and other similar materials against the effects of fire, such as filing cabinet does not offer adequate protection for data storage materials, such as disk packs, tape reels, magnetic cards, microfilm and similar materials that are easily damaged by heat and high humidity. High humidity often occurs in such a filing cabinet when the moisture which is chemically bound in the insulation of the filing cabinet is driven off by heat. Various testing organizations have set maximum limits on the temperature and humidity which are permitted to exist in containers approved for the storage of the aforementioned easily damageable materials. For example. The Underwriters Laboratories. Inc.. sets a maximum temperature of l5()F. and a maximum relative humidity of 85%.

The insulated inner container 1] of this invention permits the use of easily damageable foamed plastic insulation 41 by providing inner and outer sheet metal panels 31 and 33 to protect the insulation against mechanical injury. To prevent the flow of heat from the outer panel 33 to the inner panel 3l over the top of the lower portion 27 of the container, the edge portions of these panels which extend over the top of the container are spaced apart and turned down into a groove 49 formed in the top of the insulation 4]. The groove is filled with a thermal barrier comprising an adhesive sealant 55. This groove and its sealant are positioned near the inner surface of the layers of insulation 41. The gasket 69 of the cover 29 engages the top surface of the lower portion 27 of the inner container outwardly of this groove and thermal barrier.

To further assist in preventing a temperature increase in the inner container 1] upon exposure to tire. the metal inner panels 31 and 61 of the container and cover are surrounded on their outer surfaces by layers of crystalline sodium thiosulfate. This chemical undergoes an endothermic reaction upon the application of heat thereto giving off moisture which absorbs heat. The absorption of heat by the moisture will cool the inner panels 31 and 61 of the insulated container and cover. The moisture given off by the crystalline soldium thiosulfate will be retained between the inner sheet metal panels 31 and 61 and the layers of aluminum foil 45 and 75 and will not increase the humidity level in the inner container.

Whereas the preferred form of the invention has been shown and described, it should be understood that there may be modifications, alternations and substitutions which can be made without departing from the teachings of this invention. Therefore, the scope of the invention should be limited only by the claims attached hereto.

We claim:

1. An insulated inner container for a fire resistive filing cabinet, including:

a lower portion having bottom. side and end walls and an open top,

said walls of said lower portion formed of inner and outer sheets of metal which are spaced apart to form a hollow enclosure with said inner and outer sheets of metal cooperating to form the top surfaces of said side and end walls,

insulating material installed in said hollow enclosure of said walls.

a groove formed in said insulating material at the top surfaces of said side and end walls.

said inner and outer sheets of metal having downturned edges extending into said groove on opposite sides of the groove. and

a thermal barrier of heat resistant adhesive filling said groove. and

a removable cover for closing said open top of said lower portion of said container.

2. The container of claim 1 in which a gasket is carried by said cover with said gasket engaging the top surfaces of said end and side walls outwardly of said groove.

3. The container of claim 2 in which a skirt hangs from the side and rear walls of said cover with said skirt extending below the top surfaces of said end and side walls of said lower portion of the container.

4. The insulated inner container of claim 1 in which a layer of a chemical which undergoes an endothermic reaction upon the application of heat thereto is positioned against the inner sheet of metal forming the walls of the lower portion of said container.

5. The insulated inner container of claim 1 in which said removable cover includes top. bottom, side and end sheets of metal forming a hollow enclosure, insulating material is positioned in the enclosure of said cover against said top, side and end sheets of metal. and a layer of a chemical which undergoes an endothermic reaction upon the application of heat thereto is positioned against the bottom sheet of metal of the coverv 6. The insulated inner container of claim 4 in which said chemical which undergoes an endothermic reaction upon the application of heat thereto is crystalline sodium thiosulfate.

7. The insulated inner container of claim 5 in which said chemical which undergoes an endothermic reaction upon the application of heat thereto is crystalline sodium thiosulfate.

8. The insulated inner container of claim 4 in which a layer of aluminum foil is positioned between said chemical layer and said insulating material.

9. The insulated inner container of claim 5 in which a layer of aluminum foil is positioned between said chemical layer and said insulating material of said removable cover. 

1. An insulated inner container for a fire resistive filing cabinet, including: a lower portion having bottom, side and end walls and an open top, said walls of said lower portion formed of inner and outer sheets of metal which are spaced apart to form a hollow enclosure with said inner and outer sheets of metal cooperating to form the top surfaces of said side and end walls, insulating material installed in said hollow enclosure of said walls, a groove formed in said insulating material at the top surfaces of said side and end walls, said inner and outer sheets of metal having downturned edges extending into said groove on opposite sides of the groove, and a thermal barrier of heat resistant adhesive filling said groove, and a removable cover for closing said open top of said lower portion of said container.
 2. The container of claim 1 in which a gasket is carried by said cover with said gasket engaging the top surfaces of said end and side walls outwardly of said groove.
 3. The container of claim 2 in which a skirt hangs from the side and rear walls of said cover with said skirt extending below the top surfaces of said end and side walls of said lower portion of the container.
 4. The insulated inner container of claim 1 in which a layer of a chemical which undergoes an endothermic reaction upon the application of heat thereto is positioned against the inner sheet of metal forming the walls of the lower portion of said container.
 5. The insulated inner container of claim 1 in which said removable cover includes top, bottom, side and end sheets of metal forming a hollow enclosure, insulating material is positioned in the enclosure of said cover against said top, side and end sheets of metal, and a layer of a chemical which undergoes an endothermic reaction upon the application of heat thereto is positioned against the bottom sheet of metal of the cover.
 6. The insulated inner container of claim 4 in which said chemical which undergoes an endothermic reaction upon the application of heat thereto is crystalline sodium thiosulfate.
 7. The insulated inner container of claim 5 in which said chemical which undergoes an endothermic reaction upOn the application of heat thereto is crystalline sodium thiosulfate.
 8. The insulated inner container of claim 4 in which a layer of aluminum foil is positioned between said chemical layer and said insulating material.
 9. The insulated inner container of claim 5 in which a layer of aluminum foil is positioned between said chemical layer and said insulating material of said removable cover. 